Magnesium sharpeners

Unfortunately I don’t know too much about chemistry. Even though the Bavarian school system provided me with 13 years of education1, the type of school I went to and the modules I picked meant that I only ever had one semester of chemistry – so please forgive me and correct me if I am using the wrong words in this blog post.

A few days ago I noticed that my magnesium sharpeners look pretty bad. The surface is now very rough, not shiny any more at all, except for some small areas. The sharpeners have been stored together with a silver plated letter opener I bought very cheap from The Pen Shop. A few erasers were also next to the sharpeners for a long period of time. I’m now wondering what caused the corrosion/tarnishing of the magnesium.

Maybe someone who knows more about chemistry can tell me what happened – so that I can avoid similar mistakes in the future.

Click to get a better look how the surface looks like now

 

My first idea what might have happened: A process similar to the one when aluminium is used to clean tarnished silver took place. The magnesium sharpeners kept the silver-plated letter opener untarnished, because magnesium is less noble than silver and therefore attracted sulphur or other chemical elements.

My alternative suggestion: Just like the chemicals from another eraser ‘ruined’ one of my wooden pencil boxes once, the chemicals from the erasers that were stored together with the magnesium sharpener changed the sharpeners’ surface, too.

Can anyone tell me what really happened to the magnesium sharpeners?

  1. I think this has now been reduced to 12 years. [↩]

Sharpening a Wopex …again

My previous experience with KUM sharpeners wasn’t very good. Some of the models I have are good, some are not so good and overall I usually prefer sharpeners from other brands.

You might remember that the Staedtler Wopex is a difficult pencil to sharpen. Nevertheless, I like it so much that on an average day it is my most used pencil. Even though sharpening it with a knife yields good results I thought I should try sharpening the Wopex in KUM’s Automatic Long Point 2M, a sharpener I haven’t used in a while because of the unsightly marks it leaves at the base of the exposed graphite1. To my surprise I got fantastic results when I used it to sharpen a Wopex.

KUM’s Automatic Long Point 2M and Staedtler's Wopex

I get best results if I align the Wopex with the top of the sharpener during the second step. If you have a Wopex and the Automatic Long Point 2M try them out. My Long Point sharpener performs much better than the dedicated Wopex sharpeners I have.

Pencil talk has a review of KUM’s Automatic Long Point 2M.

  1. These marks are one of the reason why I prefer the Deli 0635 or the Eisen 402. [↩]

KUM Correc-Combi

Today I want to show you KUM’s Correc-Combi, a sharpener in an eraser case, which I bought this April for €2.79 (~$3.65; £2.25) in Müller in Volkach, Germany.

KUM's Correc-Combi opened

The eraser

The blade of the sharpener is fixed to a plastic body which in turn is encase by (quite a large) eraser. I am sure it will take quite a long time to use this eraser up.

KUM's Correc-Combi and Staedtler's norica

The sharpener

The performance of the sharpener is quite good, certainly much better than the performance of KUM’s 400-1K. The sharpener produces thin shavings with an average thickness of 0.2 mm1.

 

KUM's Correc-Combi and Staedtler's norica

I also saw a set square from Globus by KUM for 49c (~ 65¢; 40p) in the same shop and couldn’t resist buying it. You might remember the list of sharpening angles of the different sharpeners in the KUM 400-1K blog post. When I figured these angles out, two years ago, I didn’t have a set square – so this time figuring the angle out was much easier. With about 22° the sharpening angle of the KUM Correc-Combi is very similar to the sharpening angle of Möbius+Ruppert’s grenade.

Globus by KUM's set square

Conclusion

A very good sharpener/eraser combination. The lid fits well, despite being a ‘click in’ lid (no screw thread) . The performance of the eraser is similar to that of KUM’s Correc Stick. It could be better, but is by no means bad. The performance of the sharpener is quite good and overall this eraser/sharpener combo offers very good value for money.

KUM's Correc Stick, KUM's Correc-Combi and Staedtler's norica

 

Prices: April 2012
Exchange rates: May 2012

I would like to thank Hen Chung from RAH for the Staedtler norica 132 46 HB you can see on the photos. It’s the less purple version with blind stamped “SRP”2.

The Correc-Combi is part of KUM’s Blue Ocean series. You can read a review of KUM’s Blue Ocean pencil set at pencil talk. You can also read a review of Staedtler’s norica at pencil talk.

In a previous blog post I wrote about Faber-Castell’s sharpener-eraser pen.

  1. I recently bought a calliper in Lidl, so I thought the thickness of the shavings would be a good thing to measure, especially since Lexikaliker mentions the thickness of shavings in his blog. [↩]
  2. My more purple version is blind stamped “SRL”. [↩]

KUM 400-1K

I found this KUM sharpener on a recent trip to Manchester. Unfortunately the model number is neither printed on the package nor on the sharpener, but it is probably 400-1K. Paperchase in the Trafford Centre sells these wedge-shaped magnesium-alloy sharpeners for £ 0.75 (~ € 0.82, $ 1.12). This does sound quite cheap for a sharpener that can potentially be used for a long time, but for just a few pence more  you can get the 400-1E from Cultpens, a similar magnesium sharpener that comes with two spare blades, while the 400-1K does not come with any spare blades.

KUM has a very good reputation. Like most German manufacturers in the pencil and sharpener industry they are from Franconia (more details can be found in the Eisen 402 article). Because of KUM’s reputation my expectations were quite high and I was soon disappointed when I realised that I got another sharpener from this company that does not perform as well as expected. Previous disappointments include the KUM Streamline Chrome Canister Sharpener 460S and the KUM Long Point 400-5L. My only good KUM experience with a sharpener so far is with the Kum Automatic Longpoint Sharpener, reviewed at pencil talk.

To sum my problems with the 400-1K up: it does not sharpen the pencils well. The sharpener will produce a long, continuous sliver of shavings, so the blade of the 400-1K is not blunt, but the graphite will end up with gouges or spirals. Good sharpener like the Möbius+Ruppert’s grenade, reviewed at Lexikaliker (Google translation), or the Eisen 402 do not have this problem.

The point produced by the KUM 400-1K is rather short and blunt. The sharpening angle is only about 24°. Normally you will only get a shorter point if you use a sharpener for coloured leads. The 400-1K‘s point is certainly shorter than the one produced by Möbius+Ruppert’s grenade.

Sharpener F-C Trio
(colour)		 KUM
400-1K		 M+R
grenade		 Eisen
402
Angle 

(approximately)

 29° 24° 22° 20°

Staedtler yellow pencil 134 point comparison (l-r): Faber-Castell Trio (colour sharpener), KUM 400-1K, M+R grenade, Eisen 402

Conclusion:

It is nice to have a sharpener that produces a shorter point, but I am not very enthusiastic about the KUM 400-1K. Maybe I got a “bad one”. It does perform similar to other average sharpeners, but you do not have to spend much more to get a good sharpener that will certainly outperform the 400-1K.

I would like to thank Kent for the Staedtler 134 yellow pencils used to compare the different sharpeners.

Prices and exchange rates: March 2010